pidof: reimplemented from scratch (replacing sysvinit pidof)

As the sysvinit becomes obsolete, some of the bundled tools
need to find a new home. The procps-ng project seems to be
the most suitable project for adopting the pidof tool.
This commit introduces a redesigned version of pidof
that satisfies the LSB requirements.
In corner cases the behaviour might differ from the former
one as the new version doesn't use any stat(2) calls.

pidof.1

@@ -0,0 +1,60 @@
+'\" -*- coding: UTF-8 -*-
+.\" Copyright (C) 1998 Miquel van Smoorenburg.
+.\"
+.\" This program is free software; you can redistribute it and/or modify
+.\" it under the terms of the GNU General Public License as published by
+.\" the Free Software Foundation; either version 2 of the License, or
+.\" (at your option) any later version.
+.\"
+.\" This program is distributed in the hope that it will be useful,
+.\" but WITHOUT ANY WARRANTY; without even the implied warranty of
+.\" MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+.\" GNU General Public License for more details.
+.\"
+.\" You should have received a copy of the GNU General Public License
+.\" along with this program; if not, write to the Free Software
+.\" Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+.\"
+.TH PIDOF 1 "24 Jul 2013" "" "User Commands"
+.SH NAME
+pidof -- find the process ID of a running program.
+.SH SYNOPSIS
+.B pidof
+.RB [ \-s ]
+.RB [ \-c ]
+.RB [ \-x ]
+.RB [ \-o
+.IR omitpid[,omitpid..] ]
+.RB [ \-o
+.IR omitpid[,omitpid..].. ]
+.B program
+.RB [ program.. ]
+.SH DESCRIPTION
+.B Pidof
+finds the process id's (pids) of the named programs. It prints those
+id's on the standard output.
+.SH OPTIONS
+.IP \-s
+Single shot - this instructs the program to only return one \fIpid\fP.
+.IP \-c
+Only return process ids that are running with the same root directory.
+This option is ignored for non-root users, as they will be unable to check
+the current root directory of processes they do not own.
+.IP \-x
+Scripts too - this causes the program to also return process id's of
+shells running the named scripts.
+.IP "-o \fIomitpid\fP"
+Tells \fIpidof\fP to omit processes with that process id.
+.SH "EXIT STATUS"
+.TP
+.B 0
+At least one program was found with the requested name.
+.TP
+.B 1
+No program was found with the requested name.
+
+.SH SEE ALSO
+.BR pgrep (1),
+.BR pkill (1)
+.SH AUTHOR
+Jaromir Capik <jcapik@redhat.com>